Influence of Various Strontium Formulations (Ranelate, Citrate, and Chloride) on Bone Mineral Density, Morphology, and Microarchitecture: A Comparative Study in an Ovariectomized Female Mouse Model of Osteoporosis.

Osteoporosis stands out as a prevalent skeletal ailment, prompting exploration into potential treatments, including dietary strontium ion supplements. This study assessed the efficacy of supplementation of three strontium forms-strontium citrate (SrC), strontium ranelate (SrR), and strontium chloride (SrCl)-for enhancing bone structure in 50 female SWISS mice, aged seven weeks. In total, 40 mice underwent ovariectomy, while 10 underwent sham ovariectomy. Ovariectomized (OVX) mice were randomly assigned to the following groups: OVX (no supplementation), OVX + SrR, OVX + SrC, and OVX + SrCl, at concentrations equivalent to the molar amount of strontium. After 16 weeks, micro-CT examined trabeculae and cortical bones, and whole-bone strontium content was determined. Results confirm strontium administration increased bone tissue mineral density (TMD) and Sr content, with SrC exhibiting the weakest effect. Femur morphometry showed limited Sr impact, especially in the OVX + SrC group. This research highlights strontium's potential in bone health, emphasizing variations in efficacy among its forms.

Correlation between porosity and physicochemical and biological properties of electrospinning PLA/PVA membranes for skin regeneration.

Electrospinning is an increasingly popular technique for obtaining scaffolds for skin regeneration. However, electrospun scaffolds may also have some disadvantages, as the densely packed fibers in the scaffold structure can limit the penetration of skin cells into the inner part of the material. Such a dense arrangement of fibers can cause the cells to treat the 3D material as 2D one, and thus cause them to accumulate only on the upper surface. In this study, bi-polymer scaffolds made of polylactide (PLA) and polyvinyl alcohol (PVA) electrospun in a sequential or a concurrent system were investigated in a different PLA:PVA ratio (2:1 and 1:1). The properties of six types of model materials were investigated and compared i.e.; the initial materials electrospun by the sequential (PLA/PVA, 2PLA/PVA) and the concurrent system (PLA||PVA) and the same materials with removed PVA fibers (PLA/rPVA, 2PLA/rPVA, PLA||rPVA). The fiber models were intended to increase the porosity and coherent structure parameters of the scaffolds. The applied treatment involving the removal of PVA nanofibers increased the size of interfibrous pores formed between the PLA fibers. Ultimately, the porosity of the PLA/PVA scaffolds increased from 78 % to 99 %, and the time of water absorption decreased from 516 to 2 s. The change in wettability was induced by a synergistic effect of decrease in roughness after washing out and the presence of residual PVA fibers. The chemical analysis carried out confirmed the presence of PVA residues on the PLA fibers (FTIR-ATR study). In vitro studies were performed on human keratinocytes (HaKaT) and macrophages (RAW264.7), for which penetration into the inner part of the PLAIIPVA scaffold was observed. The new proposed approach, which allows the removal of PVA fibers from the bicomponent material, allows to obtain a scaffold with increased porosity, and thus better permeability for cells and nutrients.

Macroanatomical, Histological and Microtomographic Study of the Teeth of the Komodo Dragon (Varanus komodoensis)-Adaptation to Hunting.

The present study aimed to characterize the macrostructure and microstructure of the mandibular teeth of the Komodo dragon (Varanus komodoensis) and the methods it uses to obtain food. Examinations were performed using a stereoscopic microscope, autofluorescence method, histological method and computed microtomography. A detailed macro- and micro-structural description of V. komodoensis mandibular teeth were made. The mandibular teeth are laterally flattened along their entire length and the dental crown is hooked caudally. The part of the nasal margin of the tooth crown is irregular, while the caudal margin of the tooth is characteristically serrated, except for the tooth base area. There are longitudinal grooves on the lingual and vestibular surfaces up to the lower third of the tooth height. The mandibular tooth is surrounded by a cuff made of the oral mucosa, containing the opening of the venom gland. In the histological structure of the tooth, the enamel covering the tooth crown and the dentin under the enamel are distinguished. The inside of the tooth, except its basal part, is filled with the tooth chamber, while the inside of the lower part of the tooth is filled with plicidentine, which corresponds to external furrows on the enamel. The plicidentine arrangement resembles a honeycomb. A small amount of dentine folds reach up to the tooth apex. Characteristic features of the structure of the mandibular teeth in V. komodoensis may indicate their significant role, in addition to the venom glands, in obtaining food in the natural environment of this species.

3D-Printed Polycaprolactone Implants Modified with Bioglass and Zn-Doped Bioglass.

In this work, composite filaments in the form of sticks and 3D-printed scaffolds were investigated as a future component of an osteochondral implant. The first part of the work focused on the development of a filament modified with bioglass (BG) and Zn-doped BG obtained by injection molding. The main outcome was the manufacture of bioactive, strong, and flexible filament sticks of the required length, diameter, and properties. Then, sticks were used for scaffold production. We investigated the effect of bioglass addition on the samples mechanical and biological properties. The samples were analyzed by scanning electron microscopy, optical microscopy, infrared spectroscopy, and microtomography. The effect of bioglass addition on changes in the SBF mineralization process and cell morphology was evaluated. The presence of a spatial microstructure within the scaffolds affects their mechanical properties by reducing them. The tensile strength of the scaffolds compared to filaments was lower by 58-61%. In vitro mineralization experiments showed that apatite formed on scaffolds modified with BG after 7 days of immersion in SBF. Scaffold with Zn-doped BG showed a retarded apatite formation. Innovative 3D-printing filaments containing bioglasses have been successfully applied to print bioactive scaffolds with the surface suitable for cell attachment and proliferation.

An in vitro examination of fluoride ions release from selected materials - resin-modified glass-ionomer cement (Vitremer) and nanohybrid composite material (Tetric EvoCeram).

The aim of this study was to examine a short-term fluoride ions release from selected materials - resin-modified glass ionomer -Vitremer (3M ESPE) and nanohybrid universal composite - Tetric EvoCeram (IvoclarVivadent). Release of fluoride ions [µg/mm2 /h] from Tetric EvoCeram and Vitremer into nine environments (artificial saliva - AS, deionized water and 0.9% NaCl) differing in composition of the solution and pH was determined. Six samples were prepared for each solution. In the short-term study, the measurements were taken after 1, 3, 24, 48, 72 and 168 hours. The cumulative values as well as levels of fluoride ions released at concrete time intervals were compared. Within 7 days (168 hours), both materials showed variable levels of fluoride ions release. The highest value of fluoride ions release from nanohybrid Tetric EvoCeram material was reported in deionized water (8) after 24 hours (1.550 ± 0.014 [µg/mm2/h]) and the lowest value was read in the artificial saliva AS pH 7.5 (5) after 1 hour (0.022 ± 0.001 [µg/mm2/h]). What's more, the highest value of F- release from Vitremer was found in deionized water (8) after 168 hours of immersion (24.021 ± 2.280 [µg/mm2/h]) and the lowest value was in the artificial saliva AS (without Ca2+) pH 4.5 (6) (0.303 ± 0.249 [µg/mm2/h]) after 168 hours. Cumulated release of F- after 7 days was notably higher from resin- modified glass ionomer material - Vitremer in all artificial saliva solutions (1-7) which imitated the environment of oral cavity. Therefore, we can assume that Vitremer has better remineralization potential and it may constitute a more effective method of tooth decay prevention.

Assessment of Selected Morphological, Physical and Chemical Parameters of the Teeth of the Offspring of Female Rats Exposed to 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD), Taking into Account the Protective Role of Selected Antioxidants-Preliminary Study.

The studies conducted so far indicate a negative effect of dioxins on the structure of the alveolar bone and teeth, especially in the developmental period in rats. The research aimed to analyze the indirect effect of dioxins contained in the body of female rats on the structure of the dental organ in their offspring in the neonatal period and to determine the possibility of reducing potential dioxin disorders of the structure of hard tissues in the offspring of intoxicated mothers by simultaneous administration of vitamin E or acetylsalicylic acid (ASA). Another goal of the research was to determine the level of magnesium, calcium and phosphorus contained in bone tissue as indicators of the mineralization process of hard tissues in rats, in the case of using 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and acetylsalicylic acid or α-tocopherol. The experiment was carried out on eight female rats of the Buffalo strain divided into four groups. From the offspring of eight females, the mandibles were removed from the mandibular joints, and then, after the removal of soft tissues, they were prepared for individual tests. Selected morphological, chemical and physical parameters of the teeth of the offspring of female rats from the experimental groups were analyzed. The analysis showed the effect of vitamin E and ASA on the content of Mg, Ca and P. In combination with TCDD, vitamin E and ASA, they positively inhibit the inflammatory process, preventing the leaching of Ca and Mg from the bones. ASA counteracted this phenomenon much more effectively than vitamin E. Detailed analysis of the tooth morphology showed that the molars' crowns exhibit shape disturbances under the influence of TCDD. Individual nodules in teeth T1, T2, T3 did not fuse, and the roots showed signs of hypertrophy. The study confirmed the negative effect of TCDD on tooth development. Teeth arising early in development are the most sensitive to the disorders, while the later ones are less exposed to the toxic effects of TCDD transmitted by the mother.

Evaluation of the microbial, cytotoxic and physico-chemical properties of the stainless steel crowns used in pediatric dentistry.

Preformed stainless steel crowns are used in pediatric dentistry to obtain full crown restoration of primary molar teeth. They are consider the best restoration in terms of durability and effectiveness. The purpose of this study is to evaluate microbial, cytological and physio-chemical properties to determine whereas stainless steel crown are biocompatible, safe for surrounding tissue and helpful in avoiding micro-organisms influence on the tooth tissue. Based on the results, it was determined that stainless steel crowns used in pediatric dentistry represent no cytotoxic risk to the surrounding tissues, have a low probability of developing hypersensitivity to the coronal material and also that their biological properties make them suitable to use in pediatric dentistry for the reconstruction of damaged primary molar tissue.

Influence of the intramedullary nail locking method on the stiffness of the bone-implant system.

PURPOSE: Bone fractures are one of the most commonly seen problems in veterinary traumatology. The authors of this study strive to find a new intramedullary nail, which is intended for treating femoral bone fractures for canine patients. The purpose of this study was to analyze biomechanical parameters of the intramedullary nails, which use a new bolt system concept. METHODS: Dissected femoral bones of a large breed dog were cut in order to simulate interfragmentary gap, and then the bones were stabilized using intramedullary nail with locking bolts. Bone-nail systems were subjected to cyclic loading using force which corresponds to the load on the femoral bone in the first few days after surgery. Micro-CT scans were taken of the bone samples around implant in order to determine deformation and structural parameters of bone tissue. RESULTS: The calculation of the bone-nail system stiffness was done through analysis of the force- displacement curves recorded during experimental studies. Using monocortical locking bolts resulted in smaller stiffness of the bone-nail system than using bicortical locking bolts. CONCLUSIONS: The results obtained in this study can indicate that the intramedullary nail could work well when used for treatment of bone fractures in dogs. The authors focused on using monocortical bolts which provides good stability and adequate biomechanical environment. Described fixation method is easily adjustable to a particular patient individual pa- rameters.

Aromatic Bis[aminomethylidenebis(phosphonic)] Acids Prevent Ovariectomy-Induced Bone Loss and Suppress Osteoclastogenesis in Mice.

Osteoporosis is a skeletal disease associated with excessive bone turnover. Among the compounds with antiresorptive activity, nitrogen-containing bisphosphonates play the most important role in antiosteoporotic treatment. In previous studies, we obtained two aminomethylidenebisphosphonates-benzene-1,4-bis[aminomethylidene(bisphosphonic)] (WG12399C) acid and naphthalene-1,5-bis[aminomethylidene(bisphosphonic)] (WG12592A) acid-which showed a significant antiproliferative activity toward J774E macrophages, a model of osteoclast precursors. The aim of these studies was to evaluate the antiresorptive activity of these aminobisphosphonates in ovariectomized (OVX) Balb/c mice. The influence of WG12399C and WG12592A administration on bone microstructure and bone strength was studied. Intravenous injections of WG12399C and WG12592A bisphosphonates remarkably prevented OVX-induced bone loss; for example, they sustained bone mineral density at control levels and restored other bone parameters such as trabecular separation. This was accompanied by a remarkable reduction in the number of TRAP-positive cells in bone tissue. However, a significant improvement in the quality of bone structure did not correlate with a parallel increase in bone strength. In ex vivo studies, WG12399C and WG12592A remarkably bisphosphonates reduced osteoclastogenesis and partially inhibited the resorptive activity of mature osteoclasts. Our results show interesting biological activity of two aminobisphosphonates, which may be of interest in the context of antiresorptive therapy.

Novel Nanohydroxyapatite (nHAp)-Based Scaffold Doped with Iron Oxide Nanoparticles (IO), Functionalized with Small Non-Coding RNA (miR-21/124) Modulates Expression of Runt-Related Transcriptional Factor 2 and Osteopontin, Promoting Regeneration of Osteoporotic Bone in Bilateral Cranial Defects in a Senescence-Accelerated Mouse Model (SAM/P6). PART 2.

PURPOSE: Healing of osteoporotic defects is challenging and requires innovative approaches to elicit molecular mechanisms promoting osteoblasts-osteoclasts coupling and bone homeostasis. METHODS: Cytocompatibility and biocompatibility of previously characterised nanocomposites, i.e Ca5(PO4)3OH/Fe3O4 (later called nHAp/IO) functionalised with microRNAs (nHAp/IO@miR-21/124) was tested. In vitro studies were performed using a direct co-culture system of MC3T3-E1 pre-osteoblast and 4B12 pre-osteoclasts. The analysis included determination of nanocomposite influence on cultures morphology (confocal imaging), viability and metabolic activity (Alamar Blue assay). Pro-osteogenic signals were identified at mRNA, miRNA and protein level with RT-qPCR, Western blotting and immunocytochemistry. Biocompatibility of biomaterials was tested using bilateral cranial defect performed on a senescence-accelerated mouse model, ie SAM/P6 and Balb/c. The effect of biomaterial on the process of bone healing was monitored using microcomputed tomography. RESULTS: The nanocomposites promoted survival and metabolism of bone cells, as well as enhanced functional differentiation of pre-osteoblasts MC3T3-E1 in co-cultures with pre-osteoclasts. Differentiation of MC3T3-E1 driven by nHAp/IO@miR-21/124 nanocomposite was manifested by improved extracellular matrix differentiation and up-regulation of pro-osteogenic transcripts, ie late osteogenesis markers. The nanocomposite triggered bone healing in a cranial defect model in SAM/P6 mice and was replaced by functional bone in Balb/c mice. CONCLUSION: This study demonstrates that the novel nanocomposite nHAp/IO can serve as a platform for therapeutic miRNA delivery. Obtained nanocomposite elicit pro-osteogenic signals, decreasing osteoclasts differentiation, simultaneously improving osteoblasts metabolism and their transition toward pre-osteocytes and bone mineralisation. The proposed scaffold can be an effective interface for in situ regeneration of osteoporotic bone, especially in elderly patients.

Long-Term Administration of Abacavir and Etravirine Impairs Semen Quality and Alters Redox System and Bone Metabolism in Growing Male Wistar Rats.

Highly active antiretroviral therapy (HAART) is used in HIV-infected patients. Alongside the prolongation of patients' life, adverse side effects associated with long-term therapy are becoming an increasing problem. Therefore, optimizing of HAART is extremely important. The study is aimed at evaluating the toxicity of abacavir and etravirine in monotherapy on the reproductive system, liver, kidneys, and bones in young, sexually mature, male rats. Thirty-six 8-week-old male Wistar rats randomized into three 12-animal groups received either normal saline (control), abacavir 60 mg/kg (AB group), or etravirine 40 mg/kg (ET group) once daily for 16 weeks. Semen morphology, oxide-redox state parameters (MDA, SOD, catalase, GPx, glutathione, GSH/GSSG ratio) in tissue homogenates (testes, liver, kidneys), and serum samples were studied. In bones, microcomputed tomography and a four-point bending test were performed. Total sperm count, sperm concentration, motility, and sperm morphology did not differ significantly in AB or ET groups compared to the control. In the flow cytometry of semen, an increased percentage of cells with denatured DNA was noticed for both tested drugs. However, no significant changes of oxide-redox state in testicular homogenates were found, except of increased SOD activity in the AB-receiving group. Additionally, ET significantly altered catalase and GPx in the liver and SOD activity in kidneys. Abacavir decreased catalase in the liver and GSH levels in kidneys. AB caused significant changes to bone microarchitecture (bone volume fraction, trabecular number, connectivity density, total porosity) and increased Young's modulus. Etravirine had a greater impact on macrometric parameters of bones (tibial index, mid-tibial diameter, femur length). After 4 weeks in the ET group, a lower 1,25-dihydroxyvitamin D3 serum concentration was found. The results showed that abacavir and etravirine disturb oxidative stress. An increase in the percentage of sperms with chromatin damage suggests decreased fertility in rats receiving the studied drugs. Both drugs affected bone formation in growing rats. Additionally, etravirine disturbed vitamin D metabolism.

Antiepileptic Stiripentol May Influence Bones.

Bone structure abnormalities are increasingly observed in patients chronically treated with antiepileptic drugs (AEDs). The majority of the available data concern older conventional AEDs, while the amount of information regarding newer AEDs, including stiripentol, is limited. The aim of the study was to assess the effect of stiripentol on bones. For 24 weeks, male Wistar rats, received 0.9% sodium chloride (control group) or stiripentol (200 mg/kg/day) (STP group). In the 16th week of the study, we detected lower serum PINP levels in the STP group compared to the control group. In the 24th week, a statistically significant lower 1,25-dihydroxyvitamin D3 level, higher inorganic phosphate level and higher neutrophil gelatinase-associated lipocalin (NGAL) levels in serum were found in the STP group compared to the control. Micro X-ray computed tomography of the tibias demonstrated lower bone volume fraction, lower trabecular thickness, higher trabecular pattern factor and a higher structure model index in the stiripentol group. Considering the results of this experiment on rats which suggests that long-term administration of stiripentol may impair the cancellous bone microarchitecture, further prospective human studies seem to be justified. However, monitoring plasma vitamin D, calcium, inorganic phosphate and kidney function in patients on long-term stiripentol therapy may be suggested.

The Effect of Er:YAG Laser on a Shear Bond Strength Value of Orthodontic Brackets to Enamel-A Preliminary Study.

We sought to evaluate the effects of Er:YAG laser (LightTouch, LightInstruments, Israel) conditioning on enamel roughness and shear bond strength of orthodontic brackets on enamel. Eighteen human molars (n = 9) and premolars (n = 9), were divided into 3 groups depending on the enamel conditioning method; Er:YAG laser (G1, n = 6), conventional etching with 37% orthophosphoric acid (G2, n = 6), Er:YAG laser combined with conventional etching (G3, n = 6). Er:YAG laser parameters were as follows: energy: 100 mJ, frequency: 10 Hz, exposure time: 10 s, applicator diameter: 600 µm, fluence: 35.37 J/cm2, distance: 1 mm away from a tooth, cooling: 80%. An MTS 858 MiniBionix® machine was used to determine the shear bond strength (MTS System, Eden Prairie, MN, USA). The enamel structure was assessed using X-ray microtomography (SkyScan 1172, Bruker, Kontich, Belgium). The highest values of shear bond strength were obtained in the G3 group (9.23 ± 2.38 MPa) and the lowest values in the G2 group (6.44 ± 2.11 MPa) (p < 0.05). A significant change in the enamel surface was noted after applying laser, reaching up to 9% of enamel thickness, which was not observed in the etched samples. Moreover, the Er:YAG laser-irradiated enamel surface was characterized by the greatest roughness. The combined use of an Er:YAG laser with a conventional etching improves the adhesion of composite materials to the tooth.

The assessment of temperature amplitude arising during the implant bed formation in relation to variable preparation parameters - in vitro study.

The main purpose of this study was to analyse the temperatures generated during the bone bed preparation, given the internal structure of the bone bed, the geometry of the hole, and the treatment parameters such as the type of cooling and the rotational speed of the drill. The investigated material was domestic pig ribs, in which holes were drilled three times using two drill bit systems used for Hiossen® and Paltop® dental implantation. The ThermaCAM® P640 thermal imaging camera was used for measurement of drilling temperatures. After the holes were drilled, each rib was examined using the 1172 SkyScan microtomograph, Bruker®, to compare the geometry of the machined holes. The presented study proved that larger diameter drill bits (Hiossen® drill bits) generate more heat during the machining process, as evidenced by higher temperatures obtained for the Hiossen system in each case. It was proved that rotational speed, drill bit diameter and cooling system have a significant effect on the amount of heat generated during bone tissue preparation. The density and type of bone tissue in which the hole is prepared are significant factors affecting the amount of heat generated.

Effects of efavirenz and tenofovir on bone tissue in Wistar rats.

BACKGROUND: Clinical trials indicate an increased risk of osteoporosis and bone fractures in people infected with human immunodeficiency virus (HIV). The pathogenesis of bone disturbances in HIV-positive patients is unknown, but it is suggested that antiretroviral drugs may be involved. OBJECTIVES: To assess the effects of efavirenz (EF) and tenofovir (T) on bone remodeling in rats. MATERIAL AND METHODS: The study involved 36 male Wistar rats divided into 3 groups, receiving normal saline (control group - group C), efavirenz (group EF) or tenofovir disoproxil (group T). RESULTS: After 24 weeks of the study, the following observations were made: In blood serum of the EF group compared to group C, there were increased levels of tartrate-resistant acid phosphatase form 5b (TRAP) and inorganic phosphorus. In the densitometric examination, group T showed a lower total body (TB) bone mineral density (BMD) than group C. In the immunohistochemical assessment, group EF showed a higher intensity and extension of anti-tartrate resistant acid phosphatase antibodies (abTRAP) compared to group C. In the histopathological examination of the second lumbar vertebra (L2), group EF showed a lower bone surface/volume ratio (BS/BV) and higher trabecular thickness (Tb.Th) than the control group. In the histopathological examination of the femur, a lower bone surface/tissue volume (BS/TV) and lower trabecular number (Tb.N) were found in group T compared to in group C. A lower value of the Young's modulus was observed in the four-point bending trial in groups EF and T compared to group C. CONCLUSIONS: The results of this study indicate that EF affects bone microarchitecture and leads to impaired biomechanical properties of bones in rats. Additionally, the negative effect of T on bone tissue was confirmed.

Changes in the mechanical properties of femoral cartilage tissue in advanced osteoarthritis.

PURPOSE: The main goal of this article was the analysis of the changes of mechanical properties, thickness and histology of the cartilage in different regions of the femur head in advanced stage of the osteoarthritis. METHODS: The study material consisted of cylindrical specimens (9.7 mm) prepared form proximal epiphysis of the human femur bone after hip arthroplasty. The thickness was determined from the reconstruction of the specimen from microtomography (SkyScan 1172, Bruker®) images. Mechanical properties of the cartilage tissue were identified in static indentation test conducted the use of MTS® Synergie 100 testing machine. Histological study enabled us to determine cartilage total thickness as well as location and orientation of the collagen fibers. RESULTS: Depending on the region of the head, the cartilage tissue thickness was in the range (0.74-2.23 mm). The lowest thickness values were obtained for the R5 region and the lowest for R4. Samples from R1-R4 regions differ by 24%. Measurements of cartilage tissue indentation, determined with the help of Hayes' formula, showed that the values of mechanical parameters in regions R1, R2, R3 and R5 have similar values (the difference between them is about 5.5%). Region R4, which had the smallest thickness, also had the lowest values of mechanical parameters. CONCLUSIONS: Using κ coefficients, proposed by Hayes, enabled us to obtain similar values of mechanical parameters in the regions R1, R2, R3 and R5, despite differences in cartilage tissue thickness. The R4 region, which had the weakest mechanical parameters, was characterized by the strongest reduction of the articular cartilage tissue, which was accompanied by an unformed mass of cartilage residue originating from the abraded surface and bursa fluid.

Influence of physical training on markers of bone turnover, mechanical properties, morphological alterations, density and mineral contents in the femur of rats exposed to cadmium and/or alcohol.

The aim of the study was to investigate the effect of physical training on bone parameters of rats exposed to alcohol (Al) and/or cadmium (Cd). Young female rats were divided into one control group and six groups exposed to Cd and/or Al. Al (36% calories of diet) and Cd (20 mg Cd/kg feed) were administered with liquid diet. Half of the rats from the treated groups were subjected to treadmill training (20 m/min for 0.5 h, 4 days a week). The experiment was carried out for 5 months. Al decreased the concentration of calcium (Ca) and iron (Fe) in the femur, whereas Cd and Cd + Al intake reduced the contents of Ca, Fe and zinc. Al and/or Cd caused an increase in both C-terminal telopeptide of type I collagen (CTX1; bone resorption marker) and osteocalcin (OC; formation indicator) and enhanced the degree of porosity and flexural strength of the femur. Al partially prevented the loss of Fe from the bone caused by Cd, but intensified the inhibition of growth of body weight in comparison with separate exposure to Cd. In rats co-exposed to Cd + Al, the levels of CTX1 were greater compared with those treated with Al or Cd separately, and the density was less than that in rats exposed to Al separately. The training caused increases of magnesium and Ca contents, decreases in CTX1, as well as increases in OC and bone density, decreasing their porosity. The effect of training on the bone status, however, was limited (especially in rats co-exposed to Cd and Al) because of the increase in their mineralization, stimulated by exercises, was insufficient in relation to collagen production intensity. In conclusion, training had favourable effects on some bone parameters, but did not compensate for the negative effects of Al and/or Cd exposure on the poor mineralization and histopathological and morphological changes in the femur.

Oral administration of kaempferol inhibits bone loss in rat model of ovariectomy-induced osteopenia.

BACKGROUND: Postmenopausal osteoporosis and osteoporotic fractures constitute an increasing problem in developing countries. Kaempferol, isolated from seeds of Cuscuta chinensis, is an active flavonoid inhibiting in vitro osteoclast activity. The aim of the presented research was an assessment of kaempferol effect on estrogen-deficiency-induced bone structure disturbances in rats. METHODS: The study was performed on 24 Wistar female rats divided into 3 groups: SHAM - rats undergoing a "sham" surgery, OVX-C - control group of animals that underwent ovariectomy, OVX-K - rats undergoing ovariectomy and receiving kaempferol for 8 weeks (from day 56 to day 112). RESULTS: In the OVX-K group, contrary to the OVX-C one, there was no significant decrease in femoral bone mineral density (BMD). A significant increase in Young's modulus was observed in the OVX-K group compared to the OVX-C (15.33±2.51GPa vs. 11.14±1.93GPa, p<0.05). A decreased bone turnover was detected in the OVX-K group. Tissue volume ratio (BV/TV) and trabecular bone perimeter were increased in the OVX-K group compared to the OVX-C one (0.241±0.037 vs. 0.170±0.022, p<0.05 and 15.52±2.78mm vs. 9.67±3.07mm, p<0.05, respectively). CONCLUSION: Kaempferol has a beneficial influence on estrogen-deficiency-induced disturbances of bone structure in rats.

Biomechanics of diving: the influence of the swimming speed on the kinematics of lower limbs of professional divers.

PURPOSE: The aim of this study is to evaluate the influence of the swimming speed during diving on the biomechanical parameters describing the movement of selected measurement points of the lower limb in professional divers. METHODS: The study involved a group of 4 professional divers whose movement was recorded during underwater swimming at slow (approx. 0.4 m·s-1), medium (approx. 0.5 m·s-1), and fast (approx. 0.8 m·s-1) pace. RESULTS: During swimming at medium speed, the divers made a smaller displacement (along the axes Y) of the midpoint of fin than during swimming at fast speed. The range of motion in the ankle joint increased in fast speed in comparison with low and medium swimming speed. The same relationship was noted for the obtained velocity and angular acceleration in the hip, knee and ankle joints. The authors observed that during swimming at slow pace the divers choose movement ensuring high swimming comfort while the efficiency of motion is a secondary factor. On the other hand, during swimming at higher pace, the applied movement pattern ensures far greater efficiency rather than swimming comfort. CONCLUSION: The conducted analysis showed that divers adjust the movement of their lower limbs to the swimming pace.

The Negative Impact of Selective Activation of Retinoic Acid Receptors on Bone Metabolism and Bone Mechanical Properties in Rats.

BACKGROUND: Drug-induced osteoporosis is a significant health problem, as many drugs have deleterious effects on bone metabolism. Data from several studies concerning the influence of retinol on bone homeostasis are inconsistent. OBJECTIVES: The purpose of this study was to investigate the influence of tazarotene, a selective agonist of the retinoic acid receptor (RAR), on bone metabolism and bone mechanical properties in rats. MATERIAL AND METHODS: Sixteen male Wistar rats were assigned either to the group receiving tazarotene or to the control group. Serum biochemical markers of bone turnover (osteocalcin: OC, tartrate resistant acid phosphatase 5: TRACP5b, and osteoprotegerin: OPG) and the mechanical properties of bones were analyzed. RESULTS: The mean Young's modulus was 24% higher (p < 0.05) in the control group than in the group receiving tazarotene. The stiffness of femur bones was 25% lower (p < 0.05) in rats receiving tazarotene. Flexural yield stress was slightly (2%) decreased in the tazarotene group, but the difference was not statistically significant. In the tazarotene group significantly lower serum concentration of bone turnover markers were obeserved (TRACP5b: 0.86 ± 0.30 ng/mL vs. 2.17 ± 0.67 ng/mL, OC: 7.77 ± 2.28 ng/mL vs. 13.04 ± 3.54 ng/mL and OPG: 0.09 ± 0.04 ng/mL vs. 0.27 ± 0.10) than in the control group. CONCLUSIONS: Tazarotene worsened bone mechanical properties and inhibited bone turnover in rats. These results suggest that tazarotene has a negative impact on bone metabolism and that it exerts osteoporotic activity.